A communication environment of a communication system including a base station and a mobile station is deteriorated in an area distant from the base station and an area with a poor signal condition. In such cases, the relaying apparatus such as a repeater is installed to improve the communication condition. Even though the communication condition is improved by the relaying apparatus, the communication condition may still be deteriorated due to an environmental change and thus the mobile station may not be able to maintain a communication with the base station or the relaying apparatus. As such, a new base station is installed in the communication system including existing relaying apparatus and base station, in order to enhance and improve an existing communication condition.
When the new base station is installed, it has been necessary to conduct a field test (FT) before installation to obtain information about the existing communication condition in the neighborhood of an installing position. Then, based on a result of the field test, parameters of the new base station are manually adjusted and parameters of the existing base station are adjusted via EMS (Element Management System) for controlling the base station. Here, the parameters of the base station are information about an area formation such as a transmission power and a user capacity, information about handover such as an identification data (ID) of a handover destination candidate base station and an ID of a non-handover destination candidate base station, and setting information reflecting an operation policy such as communication scheduling algorithm. Conventionally, a carrier has been adjusting the parameters for a communication of the base station by creating an information file reflecting the parameters and applying the information file to the base station via EMS. Needless to say, however, such a work requires labor costs and imposes a financial burden on the carrier. This cost is referred to as CAPEX/OPEX (Capital Expenditure/Operation Expenditure). CAPEX/OPEX is a term indicative of a cost for installation and operation of an apparatus included in the system such as the base station.
As a method to reduce CAPEX/OPEX, automation of adjustment of the base station and parameter setting has been considered. As such, a technique that allows the new base station to autonomously obtain setting information of peripheral base stations and to adjust the parameters on its own has been considered (for example, see Patent Document 1).
For automated control of the communication system, on the other hand, a concept of SON (Self Organizing Network) of LTE (long Term Evolution) has also been considered. SON is a concept for automation of adjustment and parameter setting of a base station that handles LTE. Complying with SON enables reduction in cost in installment and maintenance of the base station that handles LTE. As a result, CAPEX/OPEX required from installation to operation of the base station may be reduced. Further, in addition to reduction in CAPEX/OPEX, such automation enables to avoid human error.
In an LTE system, the communication system is generally configured by using FDD (Frequent Division Duplex). Therefore, in order to measure interference with the existing base station when the new base station is installed, the new base station needs to obtain information associated with a downlink signal such as existence of the downlink signal from another base station and signal intensity. As such, a function to receive the downlink signal from another base station may be provided to the base station, although it is of course costly. Alternatively, the base station may obtain the information about the downlink signal of another base station from the mobile station in communication with the base station. However, since contents and accuracy of the obtained information are changed as the mobile station moves, interference with the existing base station may not be stably measured.
In order to solve such a problem, the base station may obtain the information about the downlink signal from the repeater, instead of the mobile station, serving as the relaying apparatus. Since the repeater has an uplink signal transmission function in addition to a downlink signal receiving function and is fixedly installed, the repeater may determine existence of a received downlink signal and the signal intensity from a fixed position. Therefore, the base station may obtain more stable information by using the repeater than the information obtained by using the mobile station to measure the downlink signal.